How do you know if something is wrong with your heater?

Author: Dr. Laverne Farrell Sr.  |  Last update: Saturday, August 16, 2025

5 Common Signs of a Broken Heater
  1. Odd Noises. If you hear noises coming from your heater that you haven't noticed in the past, it might be a sign that it's broken and in need of repair. ...
  2. Heater doesn't Warm Up. ...
  3. Increase in Energy Bills. ...
  4. Automatic Safety Switch Failure. ...
  5. Some Rooms Aren't Warming Up.

When should I be worried about my heater?

A yellow flame is a clear sign that the gas is not burning properly. Dirty or partially blocked systems can produce this. It's also another sign that a call to your trusted HVAC contractor is needed to save money and keep you a bit safer.

What to check first if your heater isn t working?

Troubleshooting Tips for When Your Heater Isn't Working
  1. Check Your Thermostat Settings. ...
  2. Change or Replace the Air Filter. ...
  3. Check the Power Switch. ...
  4. Remove Debris From Vents. ...
  5. Flush the Drain Lines.

How do you diagnose heating problems?

5 Areas To Troubleshoot If Your Heater Is Not Working
  1. Wrong Thermostat Setting. Whether you have a SMART, programmable, or standard thermostat, it requires attention as you transition from hot weather to cold. ...
  2. Power Source Issues. Double-check that the power switch on your unit is in the “on” position. ...
  3. Clogged Air Filters.

How do I know if my heater needs to be replaced?

Here are a few trustworthy signs that signify it's time for a heating system replacement.
  1. 1) Energy Bills Just Keep Increasing. ...
  2. 2) Heating Repair Costs Are Climbing. ...
  3. 3) Yellow Burner Flames. ...
  4. 4) Your Heating System Makes Unusual Noises. ...
  5. 5) Visible Corrosion. ...
  6. Bonus Sign: Age Of Your System.

Top 5 Furnace Problems and How to Fix Them

How do I test my heater?

Check to see if your heating system runs well

To do this, turn on the emergency switch and then turn the thermostat reading up about ten degrees more than the indoor temperature. Expect the heating system to function after a few minutes. If this doesn't happen, press the reset button on the system.

Is it my thermostat or my heater?

Pay attention to how often your heating system cycles on and off. Frequent cycling could be a sign of thermostat problems as it struggles to maintain the desired temperature. If the system stays on for extended periods without adequately warming the house then the furnace might be working inefficiently.

What could be wrong with my heater?

If your heater doesn't start, chances are the problem stems from having a dirty furnace. Having dirt on your blower motor or flamer sensor could render your furnace unable to perform. When the blower motor is too dirty, it won't pass enough cool air to the heat exchanger, leading to equipment failure.

Where is the reset button on my furnace?

In most newer systems, the button is often directly next to the blower motor, while in older systems, it may be harder to spot as it is sometimes underneath or behind the motor. The reset button is often made of yellow or red plastic and marked with a large “R ” to make it easier to spot.

What is the first step when diagnosing a heater system problem?

Checking the thermostat is the first step when diagnosing a heater system problem, including ensuring the power supply, inspecting settings, and testing the sensors. Inspecting and cleaning or replacing air filters regularly is essential to maintain optimal performance and efficiency of the heater system.

How do I know if my heater is bad?

Common signs that indicate a broken heater

One common sign is weak or no airflow coming from the vents. If you notice that the air coming out of your vents is significantly weaker than usual or there is no airflow at all, it could mean that your heater's fan or blower motor is malfunctioning.

How much is a new heater?

You'll be looking at a different cost depending on the location of the furnace, the size of your home, and the type of furnace. But the average cost per unit can range anywhere from $2,672 - $6,575. The national average is $4,820 - $9,350 for a full furnace installation.

Why does my heater not feel hot?

Ensure your thermostat has not been set to a lower setting by someone else. Check your thermostat's batteries and replace any that are exhausted or defective. Clean all of the parts of your furnace, especially the ones that are susceptible to dust and dirt.

What is a typical indication of heater problems?

Signs your heating system needs professional repair include unusual noises, inconsistent or insufficient heat, frequent cycling, and increased energy bills. Other indicators are strange odors, a malfunctioning thermostat, and visible wear or damage to components.

Why is my house not heating up to temperature?

This problem often points to inadequate circulation of warm air. It could be due to blocked vents, a failing HVAC fan, or issues with the furnace itself. Ensure that furniture or drapes are not blocking your vents. Also, check if your furnace's filter is clean, as a dirty filter can restrict airflow.

How long do heaters typically last?

The Average Furnace Lifespan

A well-maintained furnace can last at least 15 to 20 years, but completing annual maintenance and being diligent with repairs can extend its life even longer.

Why is my heater running but no heat?

When you turn the furnace on but no heat comes out, there may be an obstruction. Dirty air filters restrict airflow, which can make it feel like not much heated air is coming out of your vents. Check the furnace filter and replace it if its surface is covered with contaminants.

How do you know if your furnace needs to be reset?

Why Your Furnace May Need To Be Reset
  1. The furnace has overheated: When your furnace runs too hot, it triggers a safety shut-off to prevent damage. ...
  2. The fuel supply is empty: Your furnace can't generate heat without fuel. ...
  3. The gas valve is shut: A closed valve blocks the fuel supply.

Is it safe to hit the reset button on a furnace?

Mind the safety lock. When resetting your furnace, make sure to press the button only once to avoid engaging the safety lock. Reach out to professionals. In most cases, the safest course of action is to contact your go-to HVAC company if your furnace doesn't work after a power outage.

Who should I call if my heater is not working?

A licensed HVAC technician can tell you if it's a power supply or safety issue related to your heater, or if it's a larger electrical issue that an electrician will need to address.

How do I know if my thermostat or heater is bad?

A bad thermostat can be detected when your AC or furnace is not turning on, your HVAC systems are not turning off, the thermostat not responding, your HVAC system is short-cycling, the room temperature not matching the temperature displayed on the thermostat, and the programmed setting resetting themselves.

How do I make sure my heater is working?

7 Basic Tips For Fixing Your Heater Like a Pro
  1. See if the thermostat is responding. ...
  2. Check the thermostat settings. ...
  3. Change the air filter. ...
  4. Check the circuit breakers. ...
  5. Check the ON/OFF switch. ...
  6. Open and securely close the furnace door. ...
  7. Check the gas valve by your furnace.

How do I know if my heater is broken?

That's why our team has decided to compile a list of the signs you'll notice when your heater is broken.
  1. Odd Noises. ...
  2. Heater doesn't Warm Up. ...
  3. Increase in Energy Bills. ...
  4. Automatic Safety Switch Failure. ...
  5. Some Rooms Aren't Warming Up.

Why did my heat suddenly stop working?

Often, the issue is that the heating system is simply dirty. If your furnace has a dirty blower, the blower could cause equipment failure. The system's heat exchanger cannot work unless there's sufficient air moving across it to stop it from overheating. In short, a dirty blower can cause the heat exchanger to fail.

How do I know when my furnace thermostat needs replacing?

7 Telltale Signs Your Thermostat Needs Replacing
  1. Blank or unresponsive screen. ...
  2. Short-cycling. ...
  3. Constantly running HVAC units. ...
  4. Inaccurate thermostat temperature readings. ...
  5. Hot and cold spots. ...
  6. High energy bills. ...
  7. Old and obsolete.

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